Answer five honest questions and get one recommendation for your first account — with the weakness you should know about, whether a demo exists, and the three checks to run before you deposit a cent. Not a ranking of everything; a decision for you.
Is the "best" exchange the same for everyone? No. Deep liquidity matters when your size is large; a demo account matters when you have never placed an order; a clean derivatives screen only matters if you are going to trade derivatives. That is why this asks five questions instead of publishing one list.
Should I open more than one account? Not in your first month. One venue, one demo, one small deposit. A second account is a decision for after your journal shows a repeatable process.
What if my country is not served? Then no button will show. The comparison still teaches you what to check, and the exchanges page lists what differs by jurisdiction.
Do I need a DEX? Only if you can already explain what a seed phrase is, what happens when you lose it, and how funding and liquidation work on perpetuals. Otherwise a centralised first account is the honest answer — read the DEX guide when you are ready.