They easily last 30+ years. Do you need more?

If they are not broken, don't change them.

Newer, higher quality capacitors?

Ones rated for higher hours and higher temperature that are also good quality.

The risk of damaging something (ripping pads, esd damage etc.) is high. So don't replace them as long as the board is working. If they fail, go ahead.
You can surely get them from RS-Components or Mouser.

I thought I could replace these Aluminum Electrolytic Capacitors
https://www.ebay.com/itm/20pcs-6-3V-1000uF-6- … 872.m2749.l2649

With these Aluminum Organic Polymer Capacitors
https://www.ebay.com/itm/25-Aluminum-Organic- … 75.c10#viTabs_0

Are the Aluminum Organic Polymer Capacitors better than the Aluminum Electrolytic Capacitors ?

Put in the effort to explain what you’re trying to do and why and it will help people answer your questions.

You can get them in quantity for about 60 cents a piece from Mouser if you buy 10 or more. If you buy at least 50, it goes down to 50 cents a piece.

Anyway, what are you wanting to replace capacitors on?

Repair Mother boards and Sound cards, etc...

In my opinion it is far easier and cheaper to order parts after a device fails and you know exactly what you need.
It can be good and convenient to have some common values at hand but if you don't do it on a regular basis it is not worth it.
The stuff from mouser should be at your doorstep pretty quickly when you place an order.

And as said, don't repair what's not broken in the first place.
I learned that the hard way when I had a notebook that had a defective inverter board and I thought while I'm at it I could replace the capacitors on the display controller board, too.
What happened? I rushed and ripped a pad off that only connects to a middle layer with a via. Now the notebook has no screen at all anymore and repairing it would mean to order a complete display assembly.

I will never do that again. Especially not if the device works fine otherwise.

I remember some heated debate on this particular topic, particularly with John "Chucky" Hertell calling out everyone who suggested replacing the SMD electrolytic caps on Amiga 600/1200/4000/CD32 boards with solid-state ones, pointing out that ceramics will scorch the board and outright short on failure, and tantalums will explode.
http://wordpress.hertell.nu/?p=464

Others suggest that the only reason the Amigas and Macintoshes of the era even used SMD electrolytics then is that MLCCs and tantalums with the desired properties for signal coupling weren't available yet in the late '80s/early '90s, and they should be safe to use so long as they're being used in the correct areas (read: NOT audio or power filtering-related circuits).

I personally went with the recommended hybrid polymer/aluminum capacitors, apparently industrial-grade stuff. Should last longer than the stock caps if soldered down properly, though when you're working on something like an A1200, A4000 or CD32, trace damage from leaked electrolyte is a major concern if they haven't been recapped in time. They're like slower-acting Varta NiCd barrel batteries. (Even worse, A4000 boards have those too, next to the SIMM slots...)

Intel486dx33 wrote:

What is the best replacement for Aluminum Electrolytic Capacitors ?
To prolong functionality of electronics.

If the device is working correctly and it is not made in USSR, the best replacement is to don't replace anything. 😀 I know only one kind of capacitors that may die at any time and should be replaced if seen, it's Soviet-era capacitors of type K50-6 with "G" letter on case (which made in Armenian republic of USSR). Any other does not need to be replaced until they dead.

The replacement operation can be harmful to device if the human who does the task is not much skilled. Also, in most places well-done capacitors can work for many decades and don't loss their capacitance or enlarge ESR. So the replacement is useless in most cases.