The verdict
For a lean B2B founder, Lemlist is the better all-rounder. The reason is consolidation: it folds list-building, warmup, multichannel sequencing, and AI reply handling into one subscription, so you're not stitching a separate database and a separate sender together while you're the only person running the engine. The 650M+ lead database alone often replaces a tool you'd otherwise pay for.
Mailshake wins on price and on focus. If your motion is genuinely email-led, you already have your lists, and you don't want to pay for channels you won't use, its 29 USD/user/mo entry is the leaner buy. The honest caveat: add the Data Finder and a heavier tier and the cost advantage thins out, so price the bundle you'll actually run, not the starting tier.
Both cover the deliverability basics (warmup, unified inbox), so that isn't the deciding axis. The decision comes down to whether you value breadth in one place (Lemlist) or a cheaper, tighter email tool (Mailshake).