Is there a matrix tool to assist in determining the best solution for contract/agreement type to be used?
I did a quick review of the contracting tools at https://www.dau.edu/tools and didn't have much luck finding an all-encompassing, comprehensive tool like you described that would help someone weigh let's say a BPA against an IDIQ or a T&M against a CPFF but I did find a couple of different tools when you put them together might help you weigh the pros and cons of using one vs. the other (see below). Hope these are helpful to you, and you can do some of your own research on DAU.edu.
Comparison of Major Contract Types Chart: https://www.dau.edu/tools/t/Comparison-of-Major-Contract-Types-Chart
Summary: The Comparison of Major Contract Types Chart is based on the information in the Contract Pricing Reference Guides (Volume 4 – Advanced Issues in Contract Pricing, Chapter 1 - Establishing And Monitoring Contract Type), and updated for statutory/regulatory/policy changes and court decisions that have not been included in the Guides.
On the reverse side of the Chart is additional information on contract types, pricing arrangements, and incentives used in Defense Systems Management College (DSMC) courses at the Defense Acquisition University (DAU). The current version of the chart has been updated to include changes to the Defense Federal Acquisition Regulation Supplement (DFARS) resulting from Section 807 of the National Defense Authorization Act for Fiscal Year 2020 (Pub. L. 116-92) issuance of Department of Defense Instruction (DoDI) 5000.02T, Operation of the Defense Acquisition System (Incorporating Change 6, January 23, 2020), updates to the Defense Acquisition Guidebook (DAG), and a Department of Defense deviation to the Federal Acquisition Regulation (FAR) ― Class Deviation 2020-O0003 - Use of Fixed-Price Contracts for Foreign Military Sales (08 January 2020).
The chart was formatted duplex, two-sided, printing on 11 x 17 paper.
Contract Strategy Fact Sheets: https://www.dau.edu/tools/t/Contract-Strategy-Fact-Sheets
Summary: The Contract Strategy Fact Sheets are a quick guide to the various Federal Acquisition Regulation (FAR) contract strategies available for use from Agreements, Schedules and Negotiated Contracts to lesser known strategies like Broad Agency Announcements and Defense Commercial Solutions Opening. Each of the twelve fact sheets provides the regulatory references, definitions, the applicability and considerations associated with the contract strategy, along with other resources like active links to templates, training or useful websites.
Guidance on Using Incentive and Other Contract Types: https://www.dau.edu/tools/t/Guidance-on-Using-Incentive-and-Other-Contract-Types
Summary: This guidance addresses, in a comprehensive way, the considerations contacting and acquisition professionals should take into account when selecting and negotiating the most appropriate contract type for a given requirement.