Most premixed off the shelf wood conditioners are typically nothing more than ultra thinned varnish. So, it's my humble opinion to just mix your own and test on scrap until you find a mixture that works for you. It's FAR cheaper that way. What I've found that I like to use on soft woods that tend to be blotchy when stained like Pine, Poplar, Maple etc, is to make a 1/2 or 1 pound cut of shellac. I then sand lightly after each wash coat with #220 (anywhere between one and three wash coats depending on the wood) and then stain. If you're going to use a gel stain (another good idea IMHO if you are wiping rather than spraying the stain on this type of wood), then I HIGHLY recommend the GENERAL FINISHES gel stain. It's by far the smoothest and most consistant gel stain I've tried. It's ultra thick (almost like yougart) and is very easy to work with.
As always, test, test, test on pieces of scrap first. I write each step in the finishing schedule right on the back of the scrap. That way, when I find one that I like, I have a repeatable finishing schedule already in place.
FWIW.... on one project I did several years ago on some Poplar, I sanded initially down to #220 (started at #120, then #150, #180 and finally #220). I then applied three coats of a 1/2 pound cut of shellac, sanding lightly with #220 after each wash coat. I then did a coat of GF gel stain in the primary color I wanted followed by a tone coat of transtint dye dissolved in DNA, then finished with a couple of coats of varnish. It was a major PITA on the six panel doors, but the doors and molding came out beautifully with very, very little blotching. Everyone who came and looked at the house when I put it on the market, commented on the "beautiful" woodwork.