Would it be safe to assume you are in Canada and with Rogers - since these are the only 2 full featured Android phones Rogers really offers?
Coming from the X10 you are going to get a far more lightweight user interface that (even with the stock rom image) is about as close to a vanilla Android experience as there is. You are also going to get multi-touch and pinch-zoom.
I got the Liquid E in August - it was a free upgrade so the price was right. I almost immediately rooted it and installed the Liquid Community Rom (LCR_1.8). My initial reason was that it appeared that Rogers had disabled the Google Maps update that provided TomTom style turn by turn navigation. I'm told by other Rogers/Liquid users that Google Nav works for them, but it didn't for me and Rogers told me they didn't support applications. I also didn't care for all the Rogers/Acer bloatware that was installed - RogersMyAccount, urMusic, urFooz, RogersNav.
I've been reasonably happy with my Acer Liquid E - I came from a Blackberry. The pros:
- Has all of the expected hardware. Hi-rez screen, multi-touch, camera (5MP, no flash), video (480p), accelerometer, haptic feedback, speaker, reasonably decent ear buds, 3G/EDGE/WiFi/bluetooth/GPS, FM radio (but no drivers yet), microSD, microUSB, etc.
- Out of the box with Android 2.1 and expected to go to 2.2 by November.
- Snapdragon CPU - underclocked to 788Mhz. You can over clock it, but battery life will really, really, really suck.
- Fast lightweight user interface.
- Nice high resolution screen (not so good in sunlight though).
- Acer is committed to keep it updated - at least to Froyo, possibly beyound.
- Sufficient community support - not on the same scale as HTC/Samsung/Motorola, but sufficient. There are already 2 or 3 Froyo ROMS available.
- Cheap looking glossy casing. Virtually all cell phones have plastic casings, but most don't look or feel so "plasticy".
- Plastic screen bezel. Top end phones use glass, mineral crystal or "gorilla glass" screens that feel heavier and are more resistant to scratching. A screen protector is a must.
- Hardware: No IR, no flash, no 720/1080p video, no front facing camera. meh.
- Battery life is barely acceptable - but it is my understanding that currently no Android phones have really good battery life. There are higher capacity batteries available, I haven't tried any yet.
- Not as stable as my blackberry (which never, ever crashed or went crazy in 5 years). I reboot my phone probably once a day to solve instability issues. I have had issues where the touch screen just goes nuts on occasion. I had tweaked up the touch sensitivity using gScript, and a couple of days ago i restored the original settings. This seems to be better.
- Not a lot of choice in accessories. There is only 1 company currently making silicon skins and they are out of Hong Kong and sell only on eBay. Same HK based company sells extra screen protectors. PDair sells leather cases out of the US.
I suggest you go to eBay now and buy a silicon skin or leather case and a couple of extra screen protectors. If you are all day, on the go, away from a charger, you might want to look into an extra battery. While you are at it, pick up a higher capacity (8-16GB) microSD card.
Do a bit of browsing on this forum and others on the community developed ROMs. Rooting and installing a third party rom will void your warranty, but it is pretty easy to unroot and restore the factory ROM (assuming you back it up before you start). I'm going to move to a 2.2 ROM once I am satisfied that the stability is good enough (I use my phone for business all the time).
Hope this helps.