.com dominates because buyers understand it and resale demand is deepest.
.net and .org still matter, especially for short acronyms, infrastructure names, communities, and nonprofits.
.app and .dev can be strong when the name fits software or product use. Long-tail gTLDs can work, but only when the left side and extension create a coherent phrase.
NameNotifier lets you filter by TLD because the same word can have very different value depending on the extension.