If it's crap ... We'll tell you
Personally, I'd like to see Michael Bay trampled into a fine powder in the reboot, with a disclaimer that reads "No animals were harmed in the making of this motion picture. Except for Michael Bay, which wasn't a SFX."
A serious answer to your question -- although I have never been a fan of the cartoons or the movies (especially the movies) is for the designs to go retro to their origins and make the main characters the transformers...without any cartoonish human characters.
I'll pull back a little then and revise it to designs that are not overly busy. I'm thinking primarily the fight scenes where it was difficult to make out who was who. But if there is a reboot, then a fresh look to the designs is definitely a must or it just would feel like another sequel instead of a fresh start. On a side note, it would be an interesting addition to this thread if you asked Spillios to post illustrations of what they would love to see in a reboot regarding character design.
I am a HUGE fan of Beast Wars and would love to see that. The cast was small so you got to know each Maximal individually, the stories were well told (I even cried at a few of them), there were no humans beyond our ancient ancestors, and the Megatron of that series was devious and cunning. I even loved Beast Machines which a lot of people didn't care for. I would love to see high tech CGI depictions of them so long as Michael Bay, Ehrin Kruger, Roberto Orci, and Alex Kurtzman stayed a billion miles away from it.
I wasn't really talking an all CGI movie, just that I would like to see how the Beast Wars transformers would be rendered in CGI. However now that you mention it, I would prefer an all CGI movie, that way it could cut down on the human characters and just focus on the robots. Pixar and Dreamworks make plenty of all CGI movies that do well with general audiences. I don't see how Transformers can't do the same.
I know it is different. I actually wouldn't mind it though because I think the biggest complaints about the live action movies is the raunchy stuff that is not appropriate for kids. The films are PG13 but I wouldn't take my little cousins who love the TV shows to the theaters to see them because of all the sexist, racist, and toilet humor in them. The series has always been a kids show on TV and I would not mind seeing a CGI film that is more appropriate for children.
I'm not saying there can't be, but so long as Michael Bay is doing them that won't happen. I think we got a little round about in this conversation though.
All I was trying to say is that I would be interested in seeing a feature film of Beast Wars because I am a fan of that series and it would be something different but still Transformers. The plot of the original show did not involve human main characters so it would work better as an all CGI movie. It would be aimed more at kids, but many Dreamworks and Pixar movies appeal to both. The Bay films were films that should have appealed to both but instead decided to be inappropriate for kids.
If they want they could figure some other way to work humans in there to make it live action but they would have to come up with a totally different plot.