can you hit the repeaters without the antenna mounted up high? Are you looking for more range?
I made a copper pipe j pole and it works well for me but I kinda tested my range with a smaller antenna and lower wattage first. I knew it'd be a slam dunk.
If you can't touch a repeater with what you have now you might need something like a yagi.... If it kinda works, then maybe a slightly better omni directional antenna mounted up high will work.