Rather depends how much you know about what suits you (in terms of fitting), and how you feel about older versus newer. I definitely think you get more value in older.
I'm a fan of ping irons.... because you can take them to Gainsborough and get free lie adjustment while you wait. A service I have taken advantage of in the last couple of months, and used since the mid-nineties.
My set is an old set of ping S58's. They are beautiful clubs, and I hit them well (within the limits of me, not them). Unfortunately they fall foul of the groove rule and are illegal in competition, and by local rule. Standard length, and two degrees upright (green spot). So they are now my practice set. I know that I need clubs more upright, and bigger grips - more later
I put together a legal set - S56's because they have identical lofts to my S58's. That's traditional not newer fashionable 'stronger' lofts. I don't really see the point in calling a 6 iron a 7 iron, much more important to have a set with good gapping (consistent distance changes between each club) and woods and wedges that fit consistently gapped either side of your iron range. I think I picked them up at around £90 for four to wedge ( very good condition). White spot - even more upright, and half an inch longer than standard ( you can extend or shorten when re-gripping, more later). Over time I picked up a three iron, a spare seven for practice, and tour s wedges to replace my tour w's ( lovely clubs, also illegal grooves ). I also picked up, piece by piece, some titleist 910 driver/wood/hybrids to replace my 975's ( Tigers classic driver ) because they are first generation (and thus the cheapest second hand with that capability) loft/lie adjustable with a surefit hosel.
But really the most important thing, in my view, is the right grip to fit your hands and how you grip the club. Your finger tips should only just/not quite touch the heel of your hand when you grip. Standard grips were designated such when people were ickle, and are almost always unsuitable for most modern western humans.
I use MCC +4 midsize grips ( the plus 4 is less of a taper, such that the bottom half of the grip is the equivalent of four tape wraps thicker). Circa 30 quid for thirteen from aliexpress. I use three wraps of 3M gaffer tape and blow the grips on with compressed air. With the extra wraps I can use a friction fit without adhesive tape, without the clubs slipping. If you don't need such thick grips you can use multiple wraps on a standard grip to get the friction fit. I wouldnt go above four wraps, five is hard to get the grip on. If you need a thicker grip go up to jumbo. I need the extra diameter on midsize for my grip fitting, and it's tight as a drum. This also makes it possible for me to play without a glove. One less on course faff. I only use a glove in the wet. I swing fast, but not very fast, so don't get hand wear.
If you are fitting grips, then is the time to shorten or extend the clubs, cutting, or adding extension pieces with epoxy. Steel extensions for steel shafts, graphite for graphite. This is only really suitable for adding up to an inch, so the right length clubs is your best bet. If you are a giant, and need more than that, or don't want to change the swing weight, it's a re-shaft. Buying clubs in the right range to start with is better. Of course you might improve or get older and slower, and what was once right for you might not be for long. Try to think ahead of how you see your game changing over the mid term. I'm trying to get the right fitting, and to play to that. It may not work. YMMV.
Of course you need to know what suits you. Go to a fitting day, or go hit some demo clubs and grip combo. Again ping is good here, you can get some simple measurements that in conjunction with their charts will definitely get you in the ball park for your fitting range (lie, club length, grip size) and shaft characteristics (I use s300 true temper stiff iron shafts. I can't hit a regular graphite shaft for shit. YMMV). You can take this information and buy other clubs, but i'd buy ping for the lifetime free adjustment. Just the best service. Totally available on second hand. Older ping clubs are limited by the number of times you can adjust them, and the total range (circa 2 degrees) before they snap.... but that's not a problem for newer models. Anything after S56's should be okay (circa 15 years old), but check before you buy.
I've never had a length problem, but the correct fitting greatly improves consistency and accuracy.
I have a couple of original ping anser (slotline) putters (circa 1966 design), sanded and polished to look shiny, and regripped (circa £7 from aliexpress). I'm a heavy handed putter, so this lighter traditional style suits me better. I also like a more classic look.... which is why I like a 'player' type iron. Not just form over function. Look over the ball at address can contribute to confidence.
Apart from that I don't really have any strong ideas about it.