The best antenna, that is a mag mount and is just a throw on and use with very little tuning would be a Wilson 1000 or its big brother the wilson 5000-- the only difference between the 2 is the wattage they can handle-- the wilson 1000 will be great for your needs
Use a cheap antenna for awhile then use a wilson 1000 and you will notice a huge difference--Once you buy one you will not want another antenna-- because it will be hard to find one that works as good-- unless you want to get into big external coil centerloaded antennas and add it to a mag mount then there is the predator 10k, BB, Mr.coily, Fat boy etc etc
For your needs wilson 1000 kicks butt--- a K40 works pretty close to it-- the wilson is a bit more expensive
A cheaper antenna that will work good would be a TRAM Super Sparrow or something like that in the Tram line-- you can buy them new off ebay for under 20 bucks and they work as good as a wilson-- but your going to have to buy a mag mount for it-- and its a centerloaded open coil design that some guys don't care for
With the wilson you will be happy-- great RX and TX range and good for skip-- even with a stock radio
Don't get a wilson Lil Wil 500-- not as good as the 1000-- don't get a Firestick or fiberglass whip of any kind
You could use a 102 inch whip if you don't mind the length-I've had my Wilson for years-- tried other antennas and there were very few that didn't suck compared to the wilson-- the only ones were an open coil design antenna, and designs like the wilson like K40 and such
