Let me first say that this is all my opinion. Honestly, you may be better off trying them out for yourself.
Steel Droid is now up to 5.0.
Both Mavericks (as I recall) include a reboot and screenshot option in the menu when you long-press on the power button; Steel Droid 4.8 and 5.0 do not. I think that all three are based on the latest XT862 5.7.906 system update.
I've read that some people have had battery drain issues with Maverick 4.5 compared with 4.0, so that they have stayed with 4.0. I did not notice any such difference. Maverick has a configuration utility that lets you change the theme, as well as which messaging app is used. That particular utility is not working right, though. (You can run the utility and then flash the zip file that it makes on your SD card to get it to work, but that's pretty kludgy.) Steel Droid also has replaced the Blur launcher with a customized version.
The Mavericks report battery usage at 1% increments; I believe that Steel Droid does not, though.
Both SD and the Mavericks work well for me. I think that they are both fine.
On the con side, for some reason, both developers have customized the default typeface. It's arguably more attractive, but you cannot distinguish between normal type and bold face on any of these. That's important to me, as a user of the GMail app, which shows unread messages as bold text. It is almost impossible to tell unread from previously read messages in Gmail. For this reason alone, I do not use either of these ROMs.
The two that I like are Minimoto (currently at version 1.7)
and this ROM from Q9Nap on xda-developers.com
(which, unlike stock Droid 3 Gingerbread at version 2.3.4, is Gingerbread 2.3.6.) The DST ROM from Q9Nap has a different lockscreen (which you may prefer) but is otherwise indistinguishable from stock.
Minimoto is also based on the 5.7.906 update but the developer (thingonaspring on xda-developers.com) has customized it - mostly by making it much "lighter" - he's removed a lot of inefficient code, replaced the Motorola Blur messaging and MMS with stock Android versions, replaced the launcher, implemented the 1% battery reporting, etc. Many people find that it reduces battery usage, all other things being equal, compared with rooted stock; I agree, though I find the difference to be rather smaller than many others. (Where I may find my phone after 18 hours at about 60% on average with stock, with Minimoto it may be on average at about 65% to 70%.) However, there are some things missing from Minimoto, such as the car dock app (there are several good ones on the market, though.) The GMail app is not included by default, but you can install it from the market (you must also go into settings->accounts->your GMail account to turn on GMail sync.) It also removes all of the stock battery handling (nighttime mode, performance mode, etc.), which also removes the ability to turn off mobile data from settings. These are not a big deal to me, though. You can read the other differences at the Minimoto thread that I linked above.
As I said, what you need may be different from me. But, my two favorites at the moment, and the ones that I switch between, are the XT862 2.3.6 DST SafeStrap Rom GSM Compatible
from Q9Nap and Minimoto v1.7 XT862/XT860.