I've got one I named Frankenbike. Started out as a nice lightweight trail bike. Problem was I liked to jump flights of stairs, fall off the sides of mountains, get scary air and hit v ditches pretty hard.
I kept breaking it and the mountain bike rule is never just replace, always upgrade.
I finally stripped it down to frame and completely rebuilt it from the frame up. I bought a second frame and made a nice light trail bike out of the old parts and sold it.
When I built Frankenbike it was an overbuilt monster and people told me I did it all wrong. Shortly later the major bike manufacturers came out with East Coast Freeride Hardtails that pretty much copied my design.
I currently have 3....A Holdsworth lugged 531 Reynolds frame that I built 34 years ago and still ride. A XC mountain bike I built on a GT Zaskar LE hardtail frame. And a Cannondale r2000 that is mostly stock.
I have a bunch of English 3-speeds, including a nice DL-1 with chain enclosure, rear Dynohub lighting (soon to be a 5-speed) and a B73 saddle, a Raleigh Superbe, a Sport with a rare Sturmey 4-speed, an old Hercules with a top-tube shifter and a Triumph with a 3-cog cluster and Cyclo-Benelux derailleur grafted onto the 3-speed AW hub. There are also a ladies and gents pair of Bianchi 3-speeds converted to internal 5-speed shifting (2 triggers), a 6-speed Fuji Cambridge, and my only really modern bike, a Surly Pugsley.
As you can probably tell, I am not really concerned with going fast.
I have a Schwinn High Plains mountain bike. Before that I has a Huffy. I called it the Huffy & Puffy. It was as heavy as a tank, but no where near as sturdy. I would regularly rip the crank set right out of it. A friend that rode a lot recommended that I go to an actual bike store & shop. That's where I found the Schwinn. It was on sale for Father's Day, so I got it for a little under $400. This was fifteen years ago, so no telling what it would cost now. I still have it & I never have had a bit of trouble from it. I replaced the knobbys with street treads, so now I guess its more of a cross trainer. Just a good bike, one of the best investments I ever made. Oh, & its red, my signature color!
Like buying a gun, depends on what you want to do. I bicycle to work, switched from 10 speeds to 3 speeds in 1999, found them more suitable and comfortable when properly set up-Brooks saddles, generator kights and larger cogs on the rear wheel for better gear ratios. The hybrid is in the "in" thing right now, I have never found mountain bikes that satisfactory for all-around use. And vintage bikes-like vintage guns-still have plenty of life in them.
My aluminum frame mountain bike was $300 new. I can sustain an average of 16 mph on the flats.
If you spend $3,000 or 10 times the amount for a carbon frame road bike you will increase your average sustained speed around 3- 4 mph and also increase the theft rate.
My advise don't spend more than you can afford to loose if it is stolen.
I just picked up a new one last winter - bought a Prodeco Genesis 500 electric. What a great way to ride.
Pete
PS - 20 mile range w/o recharging and 18mph top end on flats - I'm guessing on that one. (Specs say 30 mile range and 20mph) but I think they are optimistic!
Like Blackhawknj said, it depends on what you want to do. Riding around the neighborhood on bike paths maybe a "fitness" type bike (Giant Escape, Specialized Sirrus, etc). doing longer rides or something speedier on the roads, look for a road bike. I ride a Raleigh RX 1.0 cyclocross bike and it's great for my 18 mile round trip ride to work.
Not knowing much about bikes other than the cheap ones didn't hold up I bought a Schwinn mountain bike with an aluminum frame and shocks front and rear. I'm sure there are much better ones out there but this one gets me down the roads around here okay.
Next to picking one up that someone threw out ,I did the next best thing, Craigslist. I found some guy that had to keep up with his buddies and buy a expensive ride. He bought the one I purchased the year prior. Its a Hybrid with disc brakes 21 speeds and comfy seat. I added a little computer to tell me when to turn around and go home.
He paid $650 plus tax I paid $200. Thats depreciation! Looks brand new.
My other ride I bought 42 years ago a Schwinn Continental. Made in Chicago. My prior ride to that is a blue Schwinn 5 speed sting ray with banana seat and ape hanger bars. Both still rideable. I am just to big for the Stingray (grandson) and to old for the Continental.
Mine has to have a motor, wide seat and tires. Spandex and helmit with a mirror and space age black glass`s dont compliment my 300 lbs. Man, if I was on one of those things going downhill you wouldnt want to be ahead of me!