Hi @baffaro! Gabby here from the Community Engagement team at Spocket.
If you're shipping to mostly US customers, it'd be best to look for US-based suppliers for faster shipping. Items on AliExpress come from China so shipping might take a while, unless you're willing to pay more for faster shipping carriers.
Have you also considered using Spocket? The platform has loads of US suppliers who can ship within the US in as fast as 1-3 days, so it's a platform that's worth checking out. You can learn more on Spocket's official website and by joining Spocket's official Facebook group. You can also respond to me here for questions you may have about the platform. In any case, hope you can check the platform out!
There are Pro's and cons to both options. But if your wanting to build a strong store over the long run, find a US Dropshipper (like sprocket or others).
Buying from Ali express may make you more profit per item, but your often selling cheap versions of stuff. The Quality is often not that great. This can turn into customers being unhappy and not coming back, Charge backs, etc.
US Based will be higher Quality, faster shipping, but you pay for what you get so it will be more expensive. This means your charging more, and/or making less profit per item. But people will be happier with what they are buying.
Ultimately the US Based will be better for your store in the long run though.