id listen to @Soxhlet before listening to myself in this subject. I just use cheapie valves too. I just replace them when i hear a leak or find water in my tank etc. As Sox stated, you can take off the handle and there is usually a 1/2" nut that can be tighten to push the ptfe packing gasket more against the shaft.
The 2 piece valves i do use are suppose to be rebuildable but ive never done it and actually used the valve after. I have rebuilt my 3 piece one a lot of time and use those over and never had a problem.
If your really concerned, Swagelok is the only company that really makes top level valves. Be prepared to spend more on the valves than the extractor and probably double. When i started importing Steel, I use to have this supplier that was a fiting and valve supplier as me to send them swagelok stuff all the time.
Just to let you all know Swagelok has a valve factory in Hong Kong too. Some of your Swagelok valve parts are manufactured in China too. Its just they only have 1 chinese distributor and they are like 5x the price we even pay…Imagine that cost.
And @clouds If you never plan to run more than a qp/hp at a time. The narrower column is going to be more efficient than the wider column. Id just stay 1.5"-2" if thats truly your end goal. Buy what you need, not what you think you need