What are your thoughts/expriences as far as the value/fun factors for these? There are now so many options in middle school and I am trying to figure out which way to nudge DS if he has trouble making up his mind.

My DD's school doesn't have an engineering club, but engineering activities are part of the math enrichment program. They are always very popular as is the engineering day the students travel to a nearby university to attend. In attendance, these programs are split pretty evenly between boys and girls.

Her school doesn't have quiz bowl at the middle school level. The students started up the chess club again last year, but it's very small and only had boys involved last year.

The math enrichment program which includes math competitions is the most popular program with an academic bent; robotics club is also very popular though boy heavy.

Fun is so subjective; would your son rather read an encyclopedia, play a game, or dismantle your old vaccuum cleaner?

Be glad your child has so many options. I've seen situations where this was a targeted area for severe cutbacks.

Chess club seems pretty self-explanatory, so it really just depends on whether your DS wants to play chess with other kids.

I'd want more information from the staff member/s leading the engineering club. What activities do they do?

I was often recruited to Academic Pentathlon teams or math competitions, which I hated. Who wants to spend a Saturday morning taking more tests? Quiz Bowl, on the other hand, was quite a lot of fun. It's a group activity, so there's the social benefit, and if your DS likes being competitive, I'd highly recommend it to him.

Does he have to pick between them? My D2 did Quiz Bowl, and it was her most beloved extra curricular activity through high school and still in college. She eventually attended some ACE summer camps (one week), both with her team and then on her own one year. It is great for gifted kids. But she also was in Robotics. And she told me recently she wishes she hadn't given up chess at the start of middle school. But I think she would have ranked them 1. QB, 2. Robotics, and 3. Chess.

She did give up some other activities (scouting, most 4H activities)around middle school time. I have no issue with that, because honestly those activities did not seem as stimulating to her as the ones she picked. We did insist on a sport, and she ended up fencing a couple times a week through high school.

Is it possible to let him try all three and then decide?
For instance, to be on a Quiz Bowl team you have to pass tryouts (at least at our school). So, your DS will understand straight away if he likes this kind of activity (he has to be quick thinker and perform well under time pressure).
Chess club mostly depends on the coach, may be fun, may be boring But substantial progress in chess is unlikely anyway without a private coach.
Engineering Club needs further researching - do you know what they are going to do there?

I became a titled player without a private coach. If you play a lot and study independently (today facilitated by chess databases and engines) it is possible. Since one can easily play and study chess outside of school, I would prioritize the other school clubs.

Ask other parents.

I believe quiz bowl is new this year but chess and engineering has been around for a while. A lot does depend on who else is in the club and there is no way of knowing until after it starts.

Perhaps not the encyclopedia but DS is a compulsive reader so quiz bowl fits. He does want to play chess with a live person so that would be the point of chess club. As far as dismantling things, I think that is very much a kid thing but I wouldn't consider DS extreme in that regard.

Who are his friends? What are they interested in? My son decided on the H.S. Robotics Club mostly because it's the club that the kids he was hanging out with at lunch decided to join. He struggles with social situations. At this point it's mostly an excuse for him to hang out with other like minded kids, while doing something he enjoys and I see it as more a social outlet than others. In my son's case he doesn't want to do anything else that smacks too much of academics.

Who the other kids are is probably as important as what activity it is especially if he can only choose one.

I am glad that the school is really into extracurricular activities. At least one of the teachers made a point of advising the kids to learn to prioritize to fit in activities. The teachers volunteer so I don't think that cutbacks are really an issue.
DS figured out a couple of years ago that he wants to play live chess with other kids without the craziness of competition. He tried a couple of tournaments but had a couple of minor negative incidents. One time a hyper-competitive parent volunteer made a huge deal of stopping the game with his own child after another volunteer already seated DS even though he technically arrived late. DS just thought it was kind of weird to go all crazy over a cheap trophy (money prizes he would have understood).

I think Quiz Bowl he would enjoy the most, both for the social aspect and the competition.

Unfortunately, it is both a scheduling issue and a time issue. Two of those are on the same day plus DS doesn't want to over-extend himself since he has other activities as well and he has always had a ton of free playtime. Like your DD, I think that he would rank Quiz Bowl ahead of the other two.

Unfortunately, he may be able to try two but not three due to scheduling issues. I think that DS would really enjoy tryouts if they have them since he is such a trivia nut and very quick. For chess club, I think that he is really just looking for casual games.

The problem for DS is that it is hard for him to find someone with whom to play. I am pretty sure that he is not willing to put in study time for chess as there are simply too many things he enjoys doing just as much.

That one is a bit hard since this is his first year at this school and it's not our neighborhood school.

I agree with you. However, this is his first year at this school and his sister is the only one from his elementary school so while he has been chatting with a lot of different kids, any "friendship" are still very new. Engineering Club is the only potential "academic" one since he is already a compulsive reader and chess is a game to him.