Even though the "next Iphone" (5, 4HD, 4S, or WHATEVER) may be announced around June, the 4th generation iPhone is still pretty amazing. I really like it even though it may not be so different from the 3GS. If you low on money, I'd say for the 4th generation.
But like everyone else advised, wait for June to see what new features come out and see if they appeal to you.
By the way, how many years did iPhone finally come to Verizon? It's been like 3 years now? lol.
My contract ends in April from my current carrier.
LTE does not factor in, mainly because none of the main companies have nationwide coverage for LTE yet. Verizon is not expected to finish their LTE deployment until 2013. Plenty of time for me to enjoy a non LTE iPhone 4. I honestly think the iPhone 5 will be a minor refresh to the line. I dont think Apple is going to bring a LTE phone when only a small minority can enjoy it. Maybe next year we will see a large upgrade in iPhone hardware.