"Comfort" style bikes are, ironically, not too comfortable in the long haul! You're sitting down too much...
I've got a hybrid that cost me $400 over ten years ago that I"ve put quite a few miles on - though I changed to skinny tires early in the game, which bumped my cruising speed up 2 mph with the same effort. I got another 2-3 mph when I went to my Trek 7500FX 2002 model (or mabe 2001) which is a lot lighter but I don't have to figure out how to ride a road bike which made me very consistently *cranky* when I tried it before. (Same crankiness happened when we got to sitting poses in yoga. SOmething about back muscles I'm lacking, I think.) That cost me hmmm... $700? Under that. With that bike I can ride with anybody I want to and keep up (though it helps that I ride a LOT, of course!!)
When I think about bikes I think of them as being like furniture. If you wnat something with good pieces parts that's built to last, you get a good one and pay for it... and build a relationship with the bike shop (the folks at mine really love cycling and bicycles and it shows; they see this stuff as a passion, not just a way to bring in dollars).