Expense-conscious investors face a tradeoff between higher yield and long-term resilience when choosing between these two bond ETFs.The State Street SPDR Portfolio Long Term Corporate Bond ETF (SPLB 0.09%) stands out for its ultra-low fees and higher yield, while the iShares iBoxx Investment Grade Corporate Bond ETF (LQD 0.01%) is larger and has held up better during tough bond markets.Both SPLB and LQD target U.S. investment-grade corporate bonds, making them core options for fixed income exposure. The mai ...