Depends on what you are expecting out of your GPS. The best GPS for mapping isn't the best GPS for lightweight, the best GPS for options such as weather radio, personal radio, and what not isn't the best for someone that doesn't need every little gadget and likes things streamlined and simple.
I have never needed anything fancy, so have used a Garmin Legend for years. I finally upgraded to the Legend HCx recently that the Texas member mentioned he is interested in selling. I bought it on Amazon.com for $153 to my door and that was cheaper than the old one cost. I love the color screen and also bought a map SDchip of Wyoming for it that shows all the land ownership. Some guys spend hundreds of dollars on GPS equipment with all kinds of bells and whistles that I just don't need.
The 450 is a great GPS. I have an iPhone and don't like to use the touch screen with bare hands when it is cold. According to Garmin the 62S has a better antenna for thick cover and I like the buttons for use with gloves on. Either one is great in my opinion. One thing to consider is that if the screen is cracked on the 62S you still might be able to use it in a pinch. I wish I had both to make a fair choice but my wallet is too thin.
We have been using the etrex forever and really want to upgrade to either the Oregon or Montana. Has anyone used both of those and prefer one over the other? The size of the montana is why we are considering the oregon. It will definitely be a backpacking tool, so we need small, and lightweight. But are there any other advantages to the Montana?
I have been using the Garmin 530 HCx for the last several years. They are the ones with a built in 5W radio and color screen. It has all the bells and whistles on it, some of which I use and some I don't. The radio, if you use them, is as good as they get. It has seven channels that use the 5W power and the remainder are just normal radio channels found in the rest of the Garmins. These radios show on a map where the person you are talking to is located. I have talked back and forth with a buddy 8 miles away over uneven, but not super steep terrain, and have listened to people over 17 miles away from a high point in the area. If you carry a GPS and a radio, this is good combo as it is one of the best GPS's Garmin makes and it is a very powerful radio.
I use the Oregon 450 (not t) with GPS hunting maps - great combo. Same reasons that Bitteroot mentioned. I got mine for $250 - 20% at REI a while back. They ran a promo price and then I used my 20% member discount. If you're not in a rush I've seen the Oregon heavily discounted from time to time, you just have catch it.
I have the 530 HCx and so does my wife. Its nice to be able to communicate if we separate in the backcountry to look over different areas to check in every one in a while. However, if we are just going on a trip where we plan to stay together, newish Garmin eTrex 20 is a great option. Color screen, GPS mapping, small and lightweight (in fact is nearly half of what my 530 HCX is. I personally don't need a giant 4" screen for my GPS, but everyone's needs are different. Plus that touch screen if it gets when in the rain didn't work too well, or atleast the one I used didn't so I was less than impressed with that.
I got an Oregon 450T because it was on a huge sale, actually cheaper than the 450. I have been extremely pleased. The touchscreen works with gloves on (unlike the iPhone), I can add topo maps along with Birdseye satellite images to the same sd card, and it made it through 2 rainstorms without a hitch. I actually lost it while blood tracking a deer through some extremely thick brush. Found it a week later (extremely lucky), after 2 big rainstorms with the screen facing up. There was water pooled on the screen. Opened up the battery compartment and after seeing no water, it turned on like nothing had ever happened.
Having said all of that, if money was not an issue I would get the Montana. You can add the City Navigator software and it works just like their Nuvi series in your vehicle. I believe it even gives spoken directions. For viewing on your dashboard I think the larger screen is important. Lots of options out there, but for what I do I am sold on Garmin.