Just finished a trial of both for teh past month with my agency. we run about 50k emails per week across diffrent clients.

Instantly is solid for the basics. the warmup pool is huge, inbox rotation works well, and the analytics are clean. but their a/b testing is pretty basic and the api limits can be annoying if your doing anything custom. also their support takes forever to respond sometimes.

Smartlead has better features on paper. the subsequences are nice, better webhook options, and the white label setup works. but man, the ui feels clunky compared to Instantly. and we've had more deliverability issues with Smartlead accounts even with proper warmup.

we were using Apollo for contact finding before but the data quality was hit or miss, lot of bounces that were messing with our sender reputation. been testing Prospeo for the lead enrichment side since both of these cold email tools are weak on building lists. curious what others are using for their full stack?

price wise they're basically the same once you factor in everthing. Instantly's a bit cheaper at scale but Smartlead includes more in the base plan.

we're probably sticking with Instantly for now but might keep Smartlead for specific campaigns that need the advanced sequencing.