It SHOULDN’T matter but several things can help you decide what’s best. Consider what market you want to present him to: is he going off to be a “weekender/recreational” mount with once or twice a week rides? Or is he going to a regular, working daily, competing rider? Meaning: how active will the horse be thru the winter. What climate are you in, how cold does it get? What is the horse comfortable with? How hairy IS he?
A good trainer should be able to see thru the fur but not all do, and there is always the buyer that more often than not can be easily swayed by a “pretty” horse. Not wrong, just not always most practical. Most serious buyers can and will see thru the fur but again: consider the market you wish to sell him in… what do THEY customarily do?
First world issue, petty and secondary, but also think about scars and/or blemishes. Not to hide them, always give full disclosure but the first visual (you know about first impressions..) can be softened by an initially more uniform appearance. The horse MIGHT look better unclipped if neat, clean and trimmed.
Can you do a good and neat clip job or know of someone that can/will? A bad clip is worse than a clean tho hairy horse, imo.. There are some very talented body clippers out there that can put awesome designs on an entire horse! Great idea and very fun but be thoughtful (might limit designs to butt or shoulder and something relative to the horse’s personality) if trying to SELL.
You can also hold off and offer to clip for a down payment type buyer, a new owner might like to put those awesome designs on their new horse themselves and have a different pattern in mind.
Good luck with your sale, I hope he goes to a productive and forever home : )
Sure there's right and wrong but mostly there's just a whole lotta different.