Which of these two punchdown tools should I buy?

Buy the one that matches the IDC hardware you actually have. Choose the 110 tool for 110-style contacts and the Krone tool for Krone-style contacts.

The 110 model is the more configurable tool, with a replaceable blade and high/low impact selection. The Krone model is simpler and lighter, with an integrated cutter and fold-out ancillary tools. Neither is 'better' in the abstract; the wrong blade fitted to the wrong IDC is merely a more sophisticated mistake.