in all honesty, depends on your carrier and what they offer, galaxy s phones are on all carriers, but if your referring to the og i am assuming you are with T-Mo, i hear rumors about the LG optimus g2x galaxy s smartphones are great, but if your going that route, get the nexus s, or wait for the LG so you have the latest and greatest.
if your a rooter, and are looking to root and rom this thing in the new future, here are some things you must consider:
Motorola = Locked and Encrypted Bootloaders, prevents you from doing alot of great things. The og droid was the best phone moto made with android, if they unlock the bootloaders, then their products will continue to outshine the rest
HTC = Full open Android system, some of the best android devices are HTC's, updates come fairly quickly, however the biggest flaw with HTC is in the battery life, it is crippled. hopefully they will soon have a fix for their battery issues. i know the thunderbolt will not last all day on as much use as my droid x gets before it has to be charged from being drained of battery
Samsung = Tricky one here, samsung has alot of issues going around with users since sammy doesnt update their versions of android, and are well know for pushing updates, then cancelling the push. however samsung does have great battery life, nice sturdy phones with super amoled screens, and has the full open android system. but if you like being stuck 1 - 2 versions behind the rest of us and your not a rooter. i would advise rooting to get the latest and greatest (though rooting will void your warranty)
LG = havent heard anything about a single LG phone that was impressive. the LG Ally on verizon was targeted at low end users who wanted an android but couldnt afford the latest and greatest
that is all i can tell you about, considering i have not seen a dell streak yet, or a visio phone released. or an asus. but im sure we will be seeing more and more of them
depending on what you want to do, whether its rooting and roming, or just having a blast with your android.
battery life i recommend = Motorola, Samsung
Full Open Android experience = Samsung, HTC
Updated Android Version = Motorola, HTC
Ease of use = Motorola, HTC, Samsung
so you see each phone has its own pro's and con's its what you decide and you need to go play with each highend phone that is made by these manufacturers.
im not including LG because i have not played with one, but i know LG does have some nice phones
good luck in your decision Noobster