Don't know anything about the Samsung, but I just bought the LG today and it's AWESOME! I'd read reviews that it can be sluggish with Android 2.1 with only a 600MHz processor, but I haven't experienced any major issues. There are times where you can detect an ever-so-slight lag when multitasking, but nothing to hinder productivity.
I had been looking at the HTC Desire but they're sold-out. Last night when I was checking if they were in stock yet, I noticed this one on Telus' web page and immediately fell in love. It's a gorgeous phone, slick and clean looking. Screen is plenty big enough for all your day-to-day browsing etc. And at 2/3 the price of the Desire, what's not to love? They're functionally identical (HTC has their own spin on Android OS, but nothing so startling to make me spend $150 extra) and I personally think the LG is more clean & cool looking. Plus it's a slider, which gives you the option of the keyboard OR the on-screen QWERTY.
I've always loved LG. I have an LG tv, LG headphones, and I loved my LG Keybo until I made the move to smart phones, they're just an overall solid company.
I was stoked to find out this phone has FM radio, too. I'm a big fan of the CBC, and I hate it when I'm listening to a great story in the car and then I go into a store and I have to turn it off.
Another bonus is that it actually comes with decent headphones. Not the usual big round uncomfortable ear buds that you get with most phones, but silicone in-ear buds with the usual 3 sizes of buds. They double as a headset and the radio antenna.
Also, the LG is an Android phone. Now for me, I was specifically looking for an Android phone because my whole life is pretty much on Google, from my calendar to my blog. So it just makes it that much easier for keeping everything synched. As soon as I logged in to Google on the phone, it instantly downloaded my contact list and saved me that usual hassle. It also displayed my calendar in all its multi-colour splendor, with none of that annoying third-party synchronizing stuff like I had to do with BB.
Haven't had the phone long enough to test its battery life, but with the smaller screen and the ability to use the slide-out keyboard, I'm thinking it should be pretty good. Mind you, with that FM radio, I'll probably still drain it every day. But that's pretty typical for smartphones.