Mar 15, 2011
The background: Am learning that not all Android-phone providers present the same Android user-interaction. Have had a Droid2 for a year. Hate it. (plus its gotten very slow for some reason, gps is broken, etc... phone getting replaced. but probably gonna dump Verizon anyway for T-Mobile... much better plans on T-Mobile... but I digress.) Have a Samsung Gravity SMART now. Much cleaner interface. Much better feel. (and the phone doesn't take 10-40 secs to respond as the Droid2 sometimes did.) Sales reps have told me Samsung performs unique "customization" of their Android stuff. Whatever it is, I like it.

THE QUESTION (assuming it's plausible/true that Samsung actually does "customize" Androids UI): what other manufacturers might I look at for a "better"/alternative Android UIs? HTC perhaps?

(Preferring T-Mobile service, fwiw...)
Most if not all have their own UI overlays. Motorola's is called Motoblur, Samsung's is Touchwiz, and HTC's is Sense. There is no real "better" as far as I can tell, it's all personal preference. I really like the Sense on my Sensation, but others love the Touchwiz. Go to a T-Mobile store that has working display models and play around to decide which you like.

The Nexus series and a few others (as well as any phone you're willing and able to root and flash a custom rom to) have no overlay. This is commonly referred to as "vanilla".
Most manufacturers customize the user interface, the only ones that don't and use the standard Android interface are the Google phones as far as I know, Nexus One and Nexus S.

Samsung use Touchwiz, HTC use Sense and Motorola use Motoblur?.

I'm not sure what the others are called from Sony Ericsson and LG but they also have their custom interface, launcher, overlay, skin or whatever you choose to call them.

Which you perfer is down to personnal preference, neither should really cause the problems your talking about though, but I can't say I've tried Motorola phones.
I have an HTC Desire Z. One of the things I have also noticed about the HTC Sense IU and phone is that it comes with some widgets available only on HTC phones. I use a few of these and I find they are quite useful. These widgets are not available on my friend's Nexus S. When checking out different phones, you may also want to check out the selection of widgets to see what each manufacturer offers.
I have heard others complain about Motoblur's lack of performance. Not that people don't complain about the HTC and Samsung, but I don't remember hearing about lot's of lagging complaints with them. My brother has Motorola's Droid X, and my HTC Incredible is much smoother when sliding between home screens.

I personally am a big HTC fan. I feel like HTC is a pioneer when it comes to Android Development, and Sense proves it. I do see why some do not like Sense, so I agree that it is about personal preference. Sense widgets seem to have a delay in loading, but It seems to be the nature of Sense. Once they load, NO lag.

I recommend HTC. People complain about their customer service, but, from my experience, every large corporation is the same. I will say this, HTC just officially said that my Incredible is getting a Gingerbread update, and it's been 'obsolete' for months now.