What top coat do I use on a water-base painted small table that won’

Try this:

http://nooga.com/169338/the-diy-designer-what-kind-of-topcoat-should-i-use-and-when/

Urethane will work in any gloss selection or a clear coat

https://generalfinishes.com/wood-finishes-retail/water-based-topcoats-and-sanding-sealer/high-performance-water-based-topcoat

Love it, the table "won"! How many times has this happened to me... first, how long ago did you apply the base paint? Was the table at the ideal temperature when painting, and while curing? Your confident that no oil, or other substance is under the "base paint?" I generally ask the company where I bought the "base paint" what they recommend. There is nothing more frustrating than have a table that "won" keep on "winning." That is my experience. When I have a problem paint situation, I step back, think through the prep process, I tend to like to use a "shellac" to seal the previous hidden "demons" creating a hard starting surface. The problem is what is the table going to be used for etc. There are hundreds of combination it seems. I have had good luck with both the water based and non-water based poly's. But my preferred choice is "shellac" it is very forgiving. But not near as tough as the urethane mentioned above. That is the fast easy solution.

I would go with water based clear coat, the oil based ones have that lingering smell which was a deal breaker for me.

Oil based sealant will yellow in time..on a water based paint use water based sealant that stays clear,,,Winwax polycrilic..Its what I use on furniture that I redo.