The best sling will vary per user how big are your trees, what is your preference, can you groundie tie reliably, etc.
A dead eye sling vs a whoopie vs loopie vs ultra vs eye-2-eye vs loop slings. When they’re used properly within their swl their is no reason one is better than the other except personal preference they’re all made for the job.
That said eye-2-eye and solid loop slings are a fixed length so they aren’t adjustable to fit exactly where you want them and they’re flat and wide not great for blocks,etc.
I say try anything once and you’ll find what you like. Personally I usually put my porti on a woopie throw around pop through snug and done. Follows the KISS rule and I leave my porti cow hitched on the small loop dedicated to it so it’s always there.
You certainly can't beat a straight piece of rope for versatility and price. If you can't tie it on with rope, well, you better know what your doing before you start trying to take down big trees or people could get hurt. It happens every day.
Double Bearing grab on lengthwise pulls; needs loop or length.
Should make enough and see save enough with Porty/Sling to want to buy personally new, like underwear, toothbrush etc. Should intimately know any hard or abuse history to gear w/o question.
At the end of 1 real day, Porty/Sling should be nominal expense of true usable invest-meant for prized position in kit.
Would look into pulley compression jig for pre-tightening into nose of Porty.
If even just hardware pulleys, line and prussik grab.