Hi I used a Droid and a Liquid and agree with Paul
Droid has a hardware keyboard and liquid doesn't so this is the major differentiator. Coming from a G1 looking for a KB phone ... Droid it is.
Screen, droid is better on touch sensitiveness (is that a word)
Speed, Liquid romps it although the droid seems faster on things like screen rotate (is this A2.0 ?)
Looks, the liquid is a nice enough phone but I always have a nagging feeling that it look a little cheap. The droid is fugly, one of the fugliest phones I have ever used but its a weird kind of fugly, a nice fugly ... a fugly you might get used to but then again you might end up hating.
Build quality is the droid all the way its metal its heavy, its very heavy. But it does have some odd features like the metal lip round the screen is not recessed like an iphone.
Battery, the droid battery life seems comparable with the Liquid but I think the acer shades it.
The droid has a flash
The liquid rounded corner shape is not great for getting at the buttons, its quite sleek and slippy and when I was using it this morning with gloves on** it shot up in the air as I tried to unlock it. ** hint, if wearing woollen gloves just moisten the tip of your thumb ever so slightly and voila ... touch sensitive with gloves on ... also drives iphoners mad when you don't tell them and say operation with gloves on is an android feature
Both phones have stupid / awkward positions for their power / unlock buttons (in my opinion, other people like them)
The liquid doesn't have haptic feedback on the soft buttons on the bottom and the button light time out is not linked to the screen timeout so if you are using it in the dark then suddenly you are guessing where the buttons are.
Neither phone has hard buttons, this is a PITA for me and they have different orders ...
moto: BACK MENU HOME SEARCH
liquid: HOME SEARCH BACK MENU ....
IMHO back and menu should be under the right finger as on the liquid.
The dialler on the liquid is so ugly its criminal ... ACER should be put on trial for it.
You have to root the acer to get rid of the "trial" software they put on it ... this is poor.
Both devices like to behave like a lighthouse when being charged with a bright white LED indicating charge.
The acer is a half arsed effort with no real support from Acer (eg they never included the drivers in the box) which is saved by being a very good phone. You get the impression it was a minimal effort expended phone to test the waters.
The droid is a more polished effort hampered by some weird design choices.
Which am I using day to day ? The liquid, the droid is back in the test phones cupboard and my Vodafone Magic is languishing in my drawer.
The liquid is here to stay right up until someone releases one with similar performance that doesn't look quite so cheap (Nexus One ?)
Comparing them to cars the Droid is a Hummer (the military original) and the Liquid is a Noble. The hummer droid is rock solid but isn't going to wow the female audience, the Noble droid is as fast as they come and handles great but at the end of the day you know deep down its a cheap phone and as soon as a you can get your hands on the yet to be release ferrari or lambo (HTC or Sony) then you will probably change it.