I agree with GG above. I look for a mix that has around 60-70% soil and no more than 30-40% compost/composted manure. Both of the mixes you listed look very similar but the key is the percentage of sandy loam. Keep in mind that the higher the percentage of organic components the mix contains the more settling via decomposition there will be over the first year or 2. You may lose up to 1/2 of the volume in a 50-50 mix requiring you to add more soil and compost later.

Pretty good advice here, I don't have much to add. Mostly mineral soil is what you want, it shoul not look like potting mix. The settling factor is likely to be large the first year so fill them up good. Next year you can top them off after they've settled, with a mixture of soil and compost. Eventually you should get to a state where they stay pretty full and you can add an inch of compost every year.

Oh the store representative told you the product that is far more expensive than the proper topsoil option is the best? How typical.

20 inches is much more volume than necessary for growing vegetables so I am curious why the raised beds are that tall. Is it for landscaping purposes?

The issue that happens when you raise them up that much is that they become more like containers rather than beds. When they are, say, 10 inches or lower all you have to do is to dig, aerate and amend the existing mineral soil - and than in and of itself will raise the soil level about 4 or 5 inches. Then you still have room for another 4 or 5 inches of winter mulch when the time comes. As that mulch decomposes over a couple of years the bed will continue to rise a bit.

But for a 20 inch bed you will have to amend with extra mineral soil plus compost, as gardengal said. (Be sure and leave 5 inches on the top to contain mulch - whatever height you are working with.) That is a lot of extra work and expense, plus it will take more time for all that new dead soil to fill with a living ecosystem because the current ecosystem has been buried underneath a foot and a half of purchased material.

I'm just pointing out that the extra height will mean more time, expense and work before it is alive and fully functional. It certainly can work, and there may be good reasons (like a particular landscape design) for doing it.

I mention this because I run in to a lot of people that think of raised beds as building containers - but they are not. Typically a raised bed is just

1.) defining the garden into walkways and planting areas,

2.) adding air and amendments to the existing garden soil, and then

3.) adding a small retaining structure around the defined planting beds to accommodate the added height of the aerated and amended soil.

The goal is usually to make your garden soil better rather than replace it with a new growing medium. That's because your existing garden soil, imperfect though it may be, contains important minerals and biology that you can't easily buy at a big box store.

higher raised bed is usually better, but not always. 20 inches is quite high for most crops