“Which is best?” is the wrong question.
Here is the checklist.

Where is the quote computed?

An off-chain quote asks you to trust a server; an on-chain quote is reproducible by anyone.

Our answerOn-chain — previewPlan on the Quoter contract. Rerun it yourself with a free eth_call.

Who keeps the execution surplus?

When execution beats the quote, most venues keep the difference.

Our answerReturned to the user, fee-exempt — in the contract, not the marketing.

What enforces your minimum output?

A frontend-computed minOut can be poisoned; a contract-derived floor cannot.

Our answerThe Iron Law Φ: re-derived on-chain, hard-clamped at 75%, per-leg floors; your minOut can only tighten it.

Is advertised liquidity verified?

Quotes that trust reported reserves can promise depth that is not there.

Our answerCapacity-clamped to real balanceOf holdings; unprovable pools are refused (fail-closed).

Can the operator change the rules?

Upgradeable proxies and admin keys are standing counterparty risk.

Our answerStateless Core, no proxy; fund-touching powers renounceable (the One-Way Door).

Fees, custody, identity

The baseline hygiene questions.

Our answer0.28% in-quote fee · self-custodial, funds move only at swap-time · no account, no KYC.

Can you verify solvency yourself, now?

Periodic attestations are trust; a live invariant is proof.

Our answerisSolvent() — free to call, any block; the conserves guard makes insolvency UNREACHABLE per-transaction.

Where does the yield come from?

If you cannot name the source, you are the source.

Our answerA fixed, public emission — 180,000,000 BZPX over 7 years — plus borrower interest. No rebasing, no mystery.

Is there an oracle to attack?

Most lending exploits are oracle exploits.

Our answerNone exists: collateral and debt are the same asset (BZPX), so no price feed is ever consulted.

What do locks actually pay?

Boosts should be a formula, not a promo.

Our answerQuadratic lock boost, 1.10× (1y) to 2.75× (7y) — a public curve in the contract, not a campaign.

Can you borrow without selling?

Exiting yield to get liquidity defeats the point.

Our answerBorrow up to 50% of effective stake against yourself; kinked rate protects exit liquidity above 80% utilisation.