I've never had a uromastyx, but a friend has one and I've handled her a couple times before. Leopard geckos are smaller and more delicate compared to malis, but they have a nice simple diet (mealworms or crickets) and don't need UVB lights or 120 F basking spots.
Mali Uromastyx on the other hand are more "sturdy" and have that cute wrinkly appearance. They can wack you with their spiky tails if you piss them off, but my friend's mali has never bitten her. They need higher temps (like beardies) and UVB (again, like beardies) but my friend claims they're more interactive. I believe they eat veggies and the occasional cricket.
A normal phase juvenile leopard gecko goes for around $20-30 and I've seen juvenile mali uromastyx for $25.
I suggest you go to a herp show or a decent pet store and handle both and see what you like best. It's all up to you since you can't have random strangers online tell you what lizard to get 
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thelastplace.tk
5.13 Leopard geckos: Cut, Skaq, Fido, Dino, Big Bertha the Bus, Clyde, Bernie, Stella, Cassidy, Clara, Hero, Q, Remy, KISS, Bean, Dexie, Tweek, Kitty.
0.1 Argentine B&W Tegu: Tindra
1.0 Bearded Dragon: Hobbes